I am trying to add custom elements including drop downs and view changing from my navigationBar, because of this I need a custom one. However when trying to set the delegate to my view controller it throws an error.
#interface MyViewController : UIViewController <MyCustomNavigationBarDelegate>
#implementation MyViewController
- (void)viewDidLoad {
[super viewDidLoad];
UINavigationController *nav = [[UINavigationController alloc] initWithNavigationBarClass:[MyCustomNavigationBar class] toolbarClass:[UIToolbar class]];
nav.navigationBar.assessmentDelegate = self;
}
The last line throws the error Property 'assessmentDelegate' not found on object of type 'UINavigationBar *' However it should be type of class MyCustomNavigationBar which clearly has the delegate:
#protocol MyCustomNavigationBarDelegate;
#interface MyCustomNavigationBar : UINavigationBar
#property (weak, nonatomic) id <MyCustomNavigationBarDelegate> assessmentDelegate;
#end
#protocol MyCustomNavigationBarDelegate <NSObject>
-(void)presentViewController:(UIAlertController *)alert;
#end
cast your navigaton Bar to MyCustomNavigationBar
MyCustomNavigationBar *switchNav = (MyCustomNavigationBar *)nav.navigationBar;
switchNav.assessmentDelegate = self
Related
I'm having the following problem.
I've created a custom view controller that has a some useful methods that I need.
This is the code in the .h
#interface MYViewController : UIViewController
- (void)method;
- (void)otherMethod;
#end
This is my init method of MYViewController class:
- (instancetype)init
{
self = [super init];
return self;
}
Then when I try to extend that class I can't set the title of the child controller. For example, in "MYOtherController.h"
#interface MYOtherViewController : MYViewController
- (void)childControllerMethod;
#end
And this is the init of MYOtherViewController:
- (instancetype)init
{
self = [super init];
return self;
}
And then, if I instantiate a MYOtherViewController object and try to set the title, it happens nothing. For example:
MYOtherViewController *controller = [[MYOtherViewController] alloc] init];
controller.title = #"Hello";
If I put this in the viewDidLoad of the MYOtherViewController class it logs that title is nil:
- (void)viewDidLoad {
NSLog(#"title: %#", self.title);
[super viewDidLoad];
}
Why can't set the title in this child class?
the title for the viewcontroller hasnt been made yet after the alloc init, you would need to set it after the viewDidLoad (which is when all the UI elements have been initialized), so what you can do is make an #property on the viewcontroller which you set after the alloc init, then in the viewDidLoad, set the title to the value of the #property
I'm using a Split View Controller for an iPad app. I'm trying to send a label change to the detailReceiving Controller from the rootSending Controll when a button is pushed. I've read through tutorials on protocols and came up with the code below. When I click the button on rootSending, nothing happens to the label on detailReceiving. Do I have to do something else with a splitViewContoller so that the label will update? Shouldn't detailReceiving change the label when it receives the message?
rootSending.h
#import <UIKit/UIKit.h>
#protocol TestDelegate <NSObject>
-(void)tester:(NSString*)testString;
#end
#interface rootSending : UIViewController
#property (nonatomic, assign) id <TestDelegate> delegate;
#end
rootSending.m
#import "rootSending.h"
#implementation rootSending
#synthesize delegate;
-(void)viewDidLoad{
}
-(IBAction)buttonPressed:(id)sender{
[delegate tester:#"button pressed"];
}
#end
detailReceiving.m
#import "detailReceiving.h"
#import "rootSending.h"
#interface detailReceiving ()<TestDelegate>{
IBOutlet UILabel *label2;
}
#end
#implementation detailReceiving
-(void)viewDidLoad{
rootSending *obj = [rootSending alloc];
obj.delegate = self ;
}
-(void)tester:(NSString *)testString{
label2.text = testString;
}
#end
First of all, never ever have an alloc without an init! But in this case, even if you did use alloc/init, it still wouldn't work because that just creates a new instance of rootSending, not the one that you have in your split view. You need to get a reference to the one you have, which you can get from the split view controller,
-(void)viewDidLoad{
rootSending *obj = (rootSending *)self.splitViewController.viewControllers.firstObject;
obj.delegate = self;
}
After Edit:
If your mate controller is embedded in a navigation controller, then you need to get the navigation controller's topViewController to get your reference.
-(void)viewDidLoad{
UINavigationController *nav = (UINavigationController *)self.splitViewController.viewControllers.firstObject;
xmlListOfItems *obj = (xmlListOfItems *)nav.topViewController;
obj.delegate = self;
}
I use this code, but "it works" doesn't happen.
DetailViewController.h
[#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#protocol ProtocolNameDelegate
-(void)DoSomething;
#end
#interface DetailViewController : UIViewController {
id<ProtocolNameDelegate> _delegate;
}
#property (strong, nonatomic) id<ProtocolNameDelegate> _delegate;
DetailViewController.m
#synthesize _delegate;
- (void)viewDidLoad
{
[super viewDidLoad];
[_delegate DoSomething];
}
MasterViewController.h
#interface MasterViewController : UITableViewController <ProtocolNameDelegate>
MasterViewController.m
-(void)DoSomething
{
NSLog(#"It works");
}
I think i have to add something like:
MasterViewController* mvc = [[MasterViewController alloc] init];
mvc._delegate = self;
But it gives an error, and by the way will it create another instance of MasterViewController?
Instead of
MasterViewController* mvc = [[MasterViewController alloc] init];
mvc._delegate = self;
write this,
DetailViewController* svc = [[DetailViewController alloc] init];
dvc._delegate = self;
You made mistake in implementation.
Abstract of implementation should be.
Create Protocol in DetailVC.
Create Property for Delegate, Synthesize, and make call.
Import DetailVC in MasterVC and include delegate in MasterVC.h
Implement protocol method in MasterVC.m
Create instance of DetailVC and assign DetailVCObj.delegate = self;
In MasterViewController.m, you need to allocate and intialise DetailViewController somewhere
DetailViewController* dvc = [[DetailViewControlleralloc] init];
dvc._delegate = self;
Also, because you have written [_delegate doSomething] in
DetailviewController's viewDidLoad method,
it means you must set dvc._delegate = self; in MasterViewController.m
before loading dvc's view (before addSubview or anything that loads view).
In UINavigationController this is child controller
.h
#protocol childProtocol <NSObject>
-(void)childMethod:(NSArray*)params;
#end
#property (strong, nonatomic) id<childProtocol>childDelegate;
#property (weak, nonatomic) parentVC *pVC;
.m
if([self.childDelegate respondsToSelector:#selector(childMethod:)]) {
[self.childDelegate performSelector:#selector(childMethod:) withObject:self.arry];
}
This is my parent controller
.m
-(void)childMethod:(NSArray *)params {
// some work
}
...
childVC *cVC = [[childVC alloc]init];
cVC.pVC = self;
But childMethod: is not getting called so I searched on internet and got this post
UINavigationControllers: How to pass value to higher (parent?) controller in stack?
I tried to create a weak reference but dont know how to use to make delegate pass data from child to parent?
Try this. Check the sample project attached
ParentViewController.h
#import <UIKit/UIKit.h>
#interface ParentViewController : UIViewController
- (void)passData:(NSString *)strText;
#end
ParentViewController.m
- (IBAction)btnGoToSecondView:(id)sender {
ChildViewController *secondVC = [[ChildViewController alloc] initWithNibName:#"ChildViewController" bundle:nil];
secondVC.delegate = self;
[self presentViewController:secondVC animated:YES completion:nil];
}
- (void)passData:(NSString *)strText {
NSLog(#"Data Passed = %#",strText);
}
ChildViewController.h
#import <UIKit/UIKit.h>
#import "ParentViewController.h"
#class ParentViewController;
#interface ChildViewController : UIViewController
#property(nonatomic, assign) ParentViewController *delegate;
#end
ChildViewController.m
- (IBAction)btnPassDataBack:(id)sender {
if([self.delegate respondsToSelector:#selector(passData:)]) {
[self.delegate passData:#"Hello"];
}
[self dismissViewControllerAnimated:YES completion:nil];
}
Sample Project
This is child controller.h
#protocol childProtocol <NSObject>
-(void)childMethod:(NSArray*)params;
#end
#property (strong, nonatomic) id<childProtocol>childDelegate;
#property (weak, nonatomic) parentVC *pVC;
.m
if([self.childDelegate respondsToSelector:#selector(childMethod:)]) {
[self.childDelegate performSelector:#selector(childMethod:) withObject:self.arry];
}
This is my parent controller.h
#import <UIKit/UIKit.h>
#import "ChildController.h"
#interface perentController : UIViewController < childProtocol >
.m
- (void)childMethod:(NSArray *)params {
// some work
}
EDITED :
And Dont Forget to add childViewOBJ.childDelegate = self; at the time of create ChildViewController's object. such like,
childVC *cVC = [[childVC alloc]init];
cVC.childDelegate = self;
cVC.pVC = self;
[self presentModalViewController:cVC animated:YES];
For More information about How to create/use of Protocol.
First of all, you are not checking for the same selector as you declared in your protocol declaration so it won't respond to that. You declared the method childMethod: whereas you are checking if your childDelegate responds to myMethod: selector which does not so it won't go into the if condition.
Also the parent view controller is missing the implementation the method childMethod: in its .m. Implement that in your parent view controller or it will crash because of not finding the exact selector definition.
Since you are using a UINavigationController, the parent view controller won't be lost till the child view controller exist so the childDelegate property must not be strong unless you intend to hold onto your delegate in child view controller for some reason.
I'm trying to access some things from another viewcontroller (iOS).
I have my ViewController.h:
#import <UIKit/UIKit.h>
#interface ViewController : UIViewController <UITextFieldDelegate> {
...
}
#end
ViewController.m:
#import "ViewController.h"
#import "ViewController2.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad
{
ViewController2.someVar = #"cakes"; // this is where I'm trying to set something in vc2
}
ViewController2.h:
#import <UIKit/UIKit.h>
#interface ViewController2 : UIViewController <UITableViewDataSource, UITableViewDelegate, UISearchDisplayDelegate>
{
...
}
#property (nonatomic, copy) NSString *someVar;
#end
ViewController2.m:
#import "ViewController2.h"
#interface ViewController2 ()
#end
#implementation ViewController2
#synthesize someVar;
etc.
But at the line where I try to access this var, it gives me the following error:
Property 'someVar' not found on object of type 'ViewController2'.
In what way would I achieve accessing this other view controller?
You have to create a ViewControlle2 object in your Viewcontroller.m.
ViewController2 *myVC2 = [[ViewController2 alloc] initWithNibName:#"ViewController2" bundle:nil];
myVC2.someVar = #"cakes";
Another way to do this is by using delegates. If you created ViewController1 in AppDelegate, you should also create ViewController2 in AppDelegate, or where ever you create your ViewControllers. Then you ViewController1 would send a message to AppDelegate to get the data from ViewController2 and vice versa. This makes ViewController1 and ViewController2 no longer dependent on each other.
So in AppDelegate.h we'd have something like this
#interface AppDelegate : NSObject <MyViewControllerDelegate>
#property (nonatomic) ViewController1 *viewController1;
#property (nonatomic) ViewController2 *viewController2;
#end
Then in both view controllers you can add this line in the .h
#property (nonatomic) id<MyViewControllerDelegate> delegate;
This just gives us a variable to use to refer to the delegate from within the ViewController's .m
You also need to create the MyViewControllerDelegate protocol, so in a file called MyViewControllerDelegate.h
#protocol MyViewControllerDelegate
- (ViewController1 *) viewController1;
- (ViewControlelr2 *) viewController2;
#end
Then when you create the ViewControllers in AppDelegate.m, you should also set AppDelegate as the ViewController's delegate.
self.viewController1 = [[ViewController1 alloc] init];
self.viewController1.delegate = self;
self.viewController2 = [[ViewController2 alloc] init];
self.viewController2.delegate = self;
So with all of this delegate set up done, you should be able to access viewController2.someVar from viewController1 through the delegate by using:
self.delegate.viewController2.someVar = #"Cakes";
Hope this isn't too long winded.